Setting up integrated SSRS and SSAS servers using AutoSPInstaller

I have a sharepoint 2010 environment with 2 WEB FRONT END SERVERS, 2 APP SERVERS and 2 DATABASE SERVERS (IN A CLUSTER).

The roles and service applications running on the individual servers in the SharePoint 2010 Farm are as follows:

Web Server 1 (SharePoint Server 2010 and Office Web Applications)

Web Server Role

Application Discovery and Load Balance Service

SharePoint 2010 Web Services

Web Server 2 (SharePoint Server 2010 and Office Web Applications)

Web Server Role

Application Discovery and Load Balance Service

SharePoint 2010 Web Services

App Server 1 (SharePoint Server 2010 and Office Web Applications)

Application Server Role

Service Proxy Role

Access Database Service

Application Registry

Business Data Connectivity Service

Central Admin Service

Excel Calculation Service

InfoPath Forms Service

Managed Metadata Service

Performance Point Service

PowerPoint Service

Secure Store Service

SharePoint Timer Service

State Service

Visio Graphics Service

Usage and Health Service

Web Analytics Service

Word Automation Service

App Server 2 (SharePoint Server 2010 and Office Web Applications)

Application Server Role

Crawler and Indexing Role

Query Role

Service Proxy Role

Search Service

Search Admin Service

SharePoint Timer Service

User Profile Service

User Profile Sync Service

DB Cluster (SQL Server 2008 R2)

Database Server Role

Failover Services

I am looking to extend this environment to include SSRS and SSAS as well. I am thinking of installing SSRS in SharePoint integrated mode on App Server 1 since based on my research I felt that SP integrated mode would be the best way to leverage both SSRS
and SharePoint. For the SSAS piece, I found that installing SSAS in SharePoint integrated mode only has some limitations. So, I am thinking of installing that as both native and SP integrated mode. However, I am not sure whether I should install both the components
(Native Analysis Services Engine Service and SP Integrated/PowerPivot System Service) on the existing App Server 1 or a completely new Server (maybe App Server 3), assuming that App Server 2 is dedicated for search only. Another option I am wondering about
is whether the PowerPivot System Service can be installed on the existing App Server 1 while the native Analysis Services Engine Service on a new server (App Server 3).

As far as the storage/database layer for the SSRS is concerned, I am thinking of using the existing database cluster for the Reporting Server database on the same database instance that already exists. And for the SSAS cube storage, I am thinking of having
a separate server for the Analysis Services Engine, although still not clear whether it needs to be clustered or not.

It would be great if you guys can share your experience on SharePoint environment that includes SSRS and SSAS as data providers, preferably in SP integrated mode. Also, what are the changes you'd have to make in the AutoSPInstallerInput.xml. If you need
any additional information, I'd be more than happy to provide that.